//
// InflatingStream.h
//
// Library: Foundation
// Package: Streams
// Module:  ZLibStream
//
// Definition of the InflatingInputStream and InflatingOutputStream classes.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_InflatingStream_INCLUDED
#define Foundation_InflatingStream_INCLUDED


#include <istream>
#include <ostream>
#include "Poco/BufferedStreamBuf.h"
#include "Poco/Foundation.h"
#if defined(POCO_UNBUNDLED_ZLIB)
#    include <zlib.h>
#else
#    include "Poco/zlib.h"
#endif


namespace Poco
{


class Foundation_API InflatingStreamBuf : public BufferedStreamBuf
/// This is the streambuf class used by InflatingInputStream and InflatingOutputStream.
/// The actual work is delegated to zlib (see http://zlib.net).
/// Both zlib (deflate) streams and gzip streams are supported.
/// Output streams should always call close() to ensure
/// proper completion of decompression.
{
public:
    enum StreamType
    {
        STREAM_ZLIB, /// Expect a zlib header, use Adler-32 checksum.
        STREAM_GZIP, /// Expect a gzip header, use CRC-32 checksum.
        STREAM_ZIP /// STREAM_ZIP is handled as STREAM_ZLIB, except that we do not check the ADLER32 value (must be checked by caller)
    };

    InflatingStreamBuf(std::istream & istr, StreamType type);
    /// Creates an InflatingStreamBuf for expanding the compressed data read from
    /// the give input stream.

    InflatingStreamBuf(std::istream & istr, int windowBits);
    /// Creates an InflatingStreamBuf for expanding the compressed data read from
    /// the given input stream.
    ///
    /// Please refer to the zlib documentation of inflateInit2() for a description
    /// of the windowBits parameter.

    InflatingStreamBuf(std::ostream & ostr, StreamType type);
    /// Creates an InflatingStreamBuf for expanding the compressed data passed through
    /// and forwarding it to the given output stream.

    InflatingStreamBuf(std::ostream & ostr, int windowBits);
    /// Creates an InflatingStreamBuf for expanding the compressed data passed through
    /// and forwarding it to the given output stream.
    ///
    /// Please refer to the zlib documentation of inflateInit2() for a description
    /// of the windowBits parameter.

    ~InflatingStreamBuf();
    /// Destroys the InflatingStreamBuf.

    int close();
    /// Finishes up the stream.
    ///
    /// Must be called when inflating to an output stream.

    void reset();
    /// Resets the stream buffer.

protected:
    int readFromDevice(char * buffer, std::streamsize length);
    int writeToDevice(const char * buffer, std::streamsize length);
    int sync();

private:
    enum
    {
        STREAM_BUFFER_SIZE = 1024,
        INFLATE_BUFFER_SIZE = 32768
    };

    std::istream * _pIstr;
    std::ostream * _pOstr;
    char * _buffer;
    z_stream _zstr;
    bool _eof;
    bool _check;
};


class Foundation_API InflatingIOS : public virtual std::ios
/// The base class for InflatingOutputStream and InflatingInputStream.
///
/// This class is needed to ensure the correct initialization
/// order of the stream buffer and base classes.
{
public:
    InflatingIOS(std::ostream & ostr, InflatingStreamBuf::StreamType type = InflatingStreamBuf::STREAM_ZLIB);
    /// Creates an InflatingIOS for expanding the compressed data passed through
    /// and forwarding it to the given output stream.

    InflatingIOS(std::ostream & ostr, int windowBits);
    /// Creates an InflatingIOS for expanding the compressed data passed through
    /// and forwarding it to the given output stream.
    ///
    /// Please refer to the zlib documentation of inflateInit2() for a description
    /// of the windowBits parameter.

    InflatingIOS(std::istream & istr, InflatingStreamBuf::StreamType type = InflatingStreamBuf::STREAM_ZLIB);
    /// Creates an InflatingIOS for expanding the compressed data read from
    /// the given input stream.

    InflatingIOS(std::istream & istr, int windowBits);
    /// Creates an InflatingIOS for expanding the compressed data read from
    /// the given input stream.
    ///
    /// Please refer to the zlib documentation of inflateInit2() for a description
    /// of the windowBits parameter.

    ~InflatingIOS();
    /// Destroys the InflatingIOS.

    InflatingStreamBuf * rdbuf();
    /// Returns a pointer to the underlying stream buffer.

protected:
    InflatingStreamBuf _buf;
};


class Foundation_API InflatingOutputStream : public std::ostream, public InflatingIOS
/// This stream decompresses all data passing through it
/// using zlib's inflate algorithm.
///
/// After all data has been written to the stream, close()
/// must be called to ensure completion of decompression.
{
public:
    InflatingOutputStream(std::ostream & ostr, InflatingStreamBuf::StreamType type = InflatingStreamBuf::STREAM_ZLIB);
    /// Creates an InflatingOutputStream for expanding the compressed data passed through
    /// and forwarding it to the given output stream.

    InflatingOutputStream(std::ostream & ostr, int windowBits);
    /// Creates an InflatingOutputStream for expanding the compressed data passed through
    /// and forwarding it to the given output stream.
    ///
    /// Please refer to the zlib documentation of inflateInit2() for a description
    /// of the windowBits parameter.

    ~InflatingOutputStream();
    /// Destroys the InflatingOutputStream.

    int close();
    /// Finishes up the stream.
    ///
    /// Must be called to ensure all data is properly written to
    /// the target output stream.
};


class Foundation_API InflatingInputStream : public std::istream, public InflatingIOS
/// This stream decompresses all data passing through it
/// using zlib's inflate algorithm.
/// Example:
///     std::ifstream istr("data.gz", std::ios::binary);
///     InflatingInputStream inflater(istr, InflatingStreamBuf::STREAM_GZIP);
///     std::string data;
///     inflater >> data;
///
/// The underlying input stream can contain more than one gzip/deflate stream.
/// After a gzip/deflate stream has been processed, reset() can be called
/// to inflate the next stream.
{
public:
    InflatingInputStream(std::istream & istr, InflatingStreamBuf::StreamType type = InflatingStreamBuf::STREAM_ZLIB);
    /// Creates an InflatingInputStream for expanding the compressed data read from
    /// the given input stream.

    InflatingInputStream(std::istream & istr, int windowBits);
    /// Creates an InflatingInputStream for expanding the compressed data read from
    /// the given input stream.
    ///
    /// Please refer to the zlib documentation of inflateInit2() for a description
    /// of the windowBits parameter.

    ~InflatingInputStream();
    /// Destroys the InflatingInputStream.

    void reset();
    /// Resets the zlib machinery so that another zlib stream can be read from
    /// the same underlying input stream.
};


} // namespace Poco


#endif // Foundation_InflatingStream_INCLUDED
